Expansible link strap



July 5, 1960 Filed July 19, 1957 ya lll 'G. IHRINGER EXPANSIBLE LINK STRAP 2 Sheets-Sheet l July 5, 1960 G. |HR|NGE 2,943,437

EXPANSIBLE LINK STRAP Filed July 19,` 195'? 2 Sheets-Sheet 2 Uil ,wkn/rap l y [hf-ngel United States Patent O EXPANSIBLE LINK STRAP Gerhard Ihringer, Pforzheim, Germany, assignor to Rodi & Wienenberger Aktiengesellschaft, Pforzheim, Germany, a firm Filed July 19, 1957, Ser. No. 672,950

Claims priority, application Germany Aug. 9, 1956 2 Claims. (Cl. 59-79) The present invention relates to expansible link straps, and more specifically to an expansible link strap for wrist ywatch and ornamental bracelets, which consists of a series of flat box-like main links arranged one behind the other in a string in the longitudinal direction of the strap and from which flat intermediate links can be pulled out against spring action to extend the length of the strap.

Link straps of this type are already known in which a tension spring extends through all the main links and their .intermediate links and is xed to the ends of the strap, whereby hinge pins connecting the main links to the intermediate links of the neighboring main links, engage the tension spring and thus divide it into individual spring sections in such a manner that these sections carry out their function like separate springs inserted in the individual links. However, separate links cannot be added to or removed from these straps owing to the fact that the tension spring extends through the entire length thereof, with `the result the strap cannot be increased or reduced in length and thereby adapted to a thick or thin wrist.

The object of the invention is, therefore, to provid'e an expansible link strap of this type which can be varied in length.

This problem is solved by adding at least at one end of the strap a plurality of links which are not interconnected by a continuous spring element but can be expanded by means of separate springs as well as separated from each other or fitted together by a novel type of connection.

Such a detachable connection may comprise a spring abutment fixed in each main link by means of a screw introduced from the underside thereof. Eac-h intermediate link has one of its ends closed by an end wall and a pressure spring is inserted between the spring abutment and said end wall and presses the intermediate link into the main link.

If the screw and consequently the spring abutment are detachable the intermediate link can be pulled entirely out of the main link.

Another possible way of making the individual links detachable from each other is attainable by using as spring abutment a strip of spring steel with hook-shaped ends. This strip is placed in the intermediate link and a pressure spring inserted between one of the hook-shaped ends of the strip and the end wall of the intermediate link. The strip extends'along the bottom of the intermediate link and through a slot in the end wall thereof and its opposite hook-shaped end engages behind the end wall of the main link and is pressed against it by the prestreSsed pressure spring acting upon the first mentioned hook-shaped end. If this link connection is to be undone, the hook engaging behind the end edge of the main link fvfice must be pushed inwards so that the pressure spring looses its hold on the one hand and' liberates the intermediate link on the other hand.

According to a third form of connection the spring abutment may be formed by a bent-up wall of the main link, the pressure spring being placed under stress between said wall and the end wall of the intermediate link. The end wall of the intermediate link engaging behind the wall of the main link, forms a hook with an upwardly bent end which is hooked into a slot provided in the bottom of the neighboring unintentionally from the slot in the bottom of the main link Iwhen the strap is in contracted state, its upwardly bent end is shaped like a hammer-head which is engaged from below by a tongshaped bottom part of the neighboring intermediate link which projects beyond the end wall bearing against the spring. When the strap is expanded, the hook is secured against unintentional disengagement by the pull to which it is subjected and can only be disengaged by gripping the pulled out intermediate link and' relieving the connecting hook from the tensional stress.

Four preferred embodiments of detachable box-like main links are illustrated by way of example in the ten iigures of the accompanying drawings, in which:

Fig. l is a top plan view of a complete expansible link strap constructed as a wrist watch bracelet;

Fig. 2 is a vertical section, on a larger scale, through the link strap;

Fig. 3 is a horizontal section of a detachable link of the strap Viewed from the underside;

Fig. 4 shows the saine link in a similar view with a differently shaped intermediate link;

Fig. 5 is a bottom view of a pair of detachable links in expanded state;

Fig. 6 shows in vertical section a pair of links with a detachable connection of diiierent construcion;

Fig. 7 shows in a similar View the same pair of links in expanded state;

Fig. 8 shows another construction of detachable links in vertical section;

Fig. 9 is a similar View showing the same links in expanded state, and

Fig. l0 is a top plan View, partly in section, of the links illustrated in Fig. 9.

Referring now to the drawings, Fig. l shows an exA pansible link strap according to the invention which consists of a series of at box-like main links A, arranged 'with their longitudinal axes in the longitudinal direction of the strap, and interposed at intermediate links B guided therein, and, for example, horns C on both sides of the latter hingedly connected therewith and serving as a means for attaching a watch ease.

In the forms of construction illustrated in Figs. 2, 3 and 5, the iiat box-like main links A consist each of an open ended carrier sleeve 1 with a bottom wall l', a top wall and two side walls 3, around which sleeve a metal shell 2 is wrapped to ornament the outer sur- 4face of the main links A. At one end of the side walls 3 of the main links A rounded lugs 3 project and form an extension thereof, these lugs 3 engaging in correspondingly shaped recesses 3 at opposite ends of the side walls 3 of the neighboring main links A, thereby avoiding as far as possible the formation of gaps between the individual strap links. Between the lugs 3 of the side walls 3 of each main link a hinge pin 4 is arranged to which the intermediate 4link B of the neighboring main link A is linked. The intermediate links B which are of sleeve shape and likewise have no end walls, have a top wall provided with an upwardly projecting nose 6, which nose engages in a longitudinal slot 7 provided in the carrier sleeve 1, thereby limiting the distance to which the intermediate links B can be pulled out of the main links A. A tension spring 3 extends through all the intermediate links B of the strap and the hinge pins 4 engage in this spring and .divide it into individual spring sections 8.

The intermediate links of several main links are detachably arranged at least at one end of the strap. In the vconstructions illustrated in Figs. 2, 3 and 5 the intermediate links B have no bottom walls, with the result that a spring abutment 9 in each main link A' can be xed on the bottom wall 1' of the carrier sleeve 1. The spring abutment 9 is provided with a screw-threaded hole 10 for this purpose, into which hole a iillister headed screw 11 is introduced from the underside of the main link A' so that its head 11 is countersunk in a recess 12 in the Vmetal shell 2 and the carrier sleeve 1 and pulls the spring abutment 9 on to the bottom Wall 1'. Figs. 2, 3, 4 and 5 show yan intermediate link B' which has one of its ends open and linked to the pin 4, whereas the opposite end is closed vby an end wall 13 between which and the spring abutment 9 a pressure spring 14 is iitted under stress, which spring presses the intermediate link B into the main link A and thus brings the main links A' so that they bear one against the other. By unscrewing the screw 11 from the spring abutment 9 the intermediate link B can be removed from the main link A' and additional main links A' introduced or removed. To prevent the hollow intermediate link B' from being too much exposed on the underside of the strap (Fig. 5) when this strap is in expanded state, bottom wall parts 15 are provided on the intermediate link B' (Fig. 4) forming a slot 15' in the middle thereof and an aperture 15" at one end of the intermediate link B', into which aperture 15" the pressure spring 14 and the spring abutment 9 can be introduced. In this case the spring abutment 9 is not drawn tightly on to the bottom 1' but the screw, not shown in the drawings, has Va cylindrical collar which bears against the abutment 9 and retains it at distance from the bottom wall 1' equal to the thickness of the material of the bottom wall parts 15. When the strap is expanded the bottom wall parts 15 slide past the screw collar on the left and right and allow the interior of the intermediate link to become visible only to a limited extent through'the slot 15' and the aperture 15".

Figs. 6 and 7 show an intermediate link B" which is closed at one of its ends by an end wall 18 and provided with a bottom wall 16 on which a spring steel strip 17 rests. This strip is, remote from the closed end of the intermediate link B", bent in the form of a hook 17 and a pressure spring 14 is inserted between said hooks 17' and said end wall 18. The strip 17 extends through the intermediate link B" in longitudinal direction thereof and passes out from the intermediate link B" through a slot aperture 19 in the end wall 18 where it `forms a downwardly bent hook 17" which engages behind an end edge 20 of the bottom wall of the main link A'. When the strap is being expanded, the strip 17, owing to its hook 17" engaging behind said end edge 20 of the bottom of the main link A', remains stationary in the main link A', whereas the end wall 18 of the intermediate link B" moves towards the hook 17' and thereby compresses the spring 14. If it is desired to disengage the connection between two main links A', the hook 1 is pressed inwards with the result that it becomes disengaged and can be pulled out of the main link A With the intermediate link B. A narrow aperture V21 is provided in the bottom wall 16 to facilitate the connection of the unhooked intermediate link B" with the main links A', in that the strip 17 is pulled out of the intermediate link B and held in this position with the aid of a-pointed instrument inserted through the aperture 21. When introducing the intermediate link B into the main link A', the strip 17 bends (Fig. 7) and, owing to the resiliency of the material from which it is made, its hook 17" springs downwards behind the end edge 20 of the bottom wall when the intermediate link B has been introduced into a sufficient depth.

In the form of construction illustrated in Figs. 8 to l0 the main links A are not connected with the intermediate links of the neighboring vmain links A by means of hinge pins but are linked together -by means of a detachable hook connection. Figs. 8 to l0 show intermediate links B'" with side walls 22 and end walls 23 and 23'. The carrier sleeve y1 has on its bottom 1' an upwardly bent end wall 1" which projects into the intermediate link B" between Ythe side walls 22 thereof. The pressure spring 14 bears against the end wall 1" of the carrier sleeve 1 and the end wall 23 of the intermediate link B" and thus holds-the intermediate link B" retracted in the main link A'. The end wall 23' of the intermediate link B" extends behind the end wall 1" `and is'bent in the shape of a hook 24 on the level of the bottom of the main link A', which hook engages a hook-in slot 25 in the bottom 1' of-the neighboring main link A' and thus forms at the same time a hinge connection between the main and intermediate links. Below the end wall 23 an extension 26 of the bottom of the intermediate link B" extends on the one hand towards the end wall 23' a distance corresponding to length of the compressed spring 14 and on the other hand beyond the end wall in the form of a fork 26'. The hook 2'4 is constructed at its free end as a hammer head 24 which is engaged from below by the fork 26 when the strapis contracted (Fig. 8), so that it cannot unhook automatically from the hook-in slot 25 in the bottom 1. When the band is stretched the'fork 26' locking the hook 24, is pulled out from under the lhammer head 24' (Figs. 9 vand l0), but inthis position the hook 24 canont automatically disengage because the tension forces acting in'thestrap are transmitted from the strap to the neighboring main-link A', with the result that the hook 24 bears in the hook-in slot 25 under tension and consequently remains locked in its connecting position.

From the above detailed description of the invention, it is believed that the construction will at once be apparent, and while there are herein shown and described four preferredembodiments of the invention, it is nevertheless to be understood that minor changes may be made therein without departing from the spirit and scopeof the invention as claimed.

Iclaim:

l. An expansible link strap for ornamental bracelets and the like'comprising the combination of a series of links the longitudinal axes of vwhich extend in the longitudinal direction of the strap, each of said links being comprised of a pair of box-like link elements including an outer sleeve-shaped link element closed on the longitudinal top, bottom and sides thereof and a similar intermediate link element slidably telescoped within said outer sleeve-shaped link element, each of said links having one of said elements hingedly connected to the other of said'elements of the next adjacent link at adjacent end portions, at least two adjacent links having their respective elements detachably connected, each of said two links having'spring strip abutment means removably connectingthe linkelements making up the said link and a biasing spring with its respective intermediate link element, each, said spring strip abutment means having a middle portion extending between the bottom of the intermediate link element and the lbiasing spring, aneinner hook-shaped end portion engageable with one extremity `of the biasing spring and an outer hook-shaped end portion which extends through an end wall of the respective intermediate link element and projects downwardly to releasably engage an end of the bottom of References Cited in the le of this patent UNITED STATES PATENTS 1,198,925 Jones et al. Sept. 19, 1916 I6 Rioux Oct. 31, 1916 King Nov. 12, 1918 Wynn Dec. 30, 1919 Mealy Feb. 17, 1925 Kollstede Oct. 6, 1925 Hart Mar. 20, 1928 Prestinari Ian. 29, 1929 Augustein Ian. 3l, 1956 FOREIGN PATENTS Great Britain June 6, 1912 Great Britain Oct. 9, 1913 

